This specification relates to data processing and information retrieval.
The Internet provides access to a wide variety of resources such as images, video or audio files, web pages for particular subjects, book articles, or news articles. A search system can identify resources in response to a text query that includes one or more search terms or phrases. The search system ranks the resources based on their relevance to the query and on measures of quality of the resources and provides search results that link to the identified resources. The search results are typically ordered for viewing according to the rank.
To search image resources, a search system can determine the relevance of an image to a text query based on the textual content of the resource in which the image is located and/or based on relevance feedback associated with the image. For example, an information retrieval score measuring the relevance of a text query to the content of a web page can be one of many factors used to generate an overall search result score for the image.
Some search systems search image resources by using “query images” as input. A query image is an image represented by data, such as a jpeg file, that is used by a search engine as input to a search processing operation. Related images can be found by processing other image data for images and identifying images that are similar in visual appearance to the query image.
In some situations, the user that is searching for a particular image may not have enough information about the image to formulate a text query to which the particular image will be identified as responsive. For example, if a user is unaware of the name of (or other identifying information for) a famous Paris café, it may difficult for the user to select a textual query that will cause an image of (or other information about) the famous Paris café to be included in the image search results (or other search results). Additionally, the user may not have access to a copy of an image of the famous Paris café, such that the user is also unable to utilize a “query image” to search for information about the famous Paris café. Thus, the user may experience difficulty in obtaining information that can help the user satisfy his or her informational need.